docs: def input(channel):
      """
      Read the value of a GPIO pin.
  
      :param channel: the channel based on the numbering system you have specified
          (:py:attr:`GPIO.BOARD`, :py:attr:`GPIO.BCM` or :py:attr:`GPIO.SUNXI`).
      :returns: This will return either :py:attr:`0` / :py:attr:`GPIO.LOW` /
          :py:attr:`False` or :py:attr:`1` / :py:attr:`GPIO.HIGH` / :py:attr:`True`).
      """
      _check_configured(channel)  # Can read from a pin configured for output
      pin = get_gpio_pin(_mode, channel)
      return sysfs.input(pin)